I would find out what happens at home ... is the child being carried at all times .... do they pick him up at first peep (no delayed gratification) does mom baby wear? Do they co sleep? Does the child play independently on the floor at home ? By the answers you will know if this is just an adjustment or are you banging your head up against the wall ... if the parents are scooping him up the minute he cries or makes any sound then you will get no where ... you have to work together or forget it ... is the child full time or part time ? If part time the parent may have to bring him full time till he transitions in and then remove a day for a few weeks and then another day for a few weeks till your at the desired days and if he reverts back they will have to bring him more days